So, I have a few drops of water showing up on my first level ceiling right about where the bathrooms are on the second level. On the second level I have two bathrooms - back to back (and the toilets are almost back to back).

I got a plumber to look at the leak. He opened up the ceiling but couldn't find the source of the leak and suggested I replace the wax ring of the guest bathroom toilet (which seem to be right above the point where the drops of water come). We did that. A few days later I noticed the leak still happening.

I have tried to "troubleshoot" the leak - first few days had no one use the guest bathroom toilet but the leak still was there. Then, switched around - had folks not used the master bathroom toilet. The leak is still there. It is not a steady drip - seems to happen a little after the toilet is used.

I am having the plumber come back and take another look at the issue. Does anyone have ideas on what might be the cause or how to better troubleshoot the issue or even be a little more intelligent when discussing with the plumber or someone else.

  • 1
    It could be that there is enough moisture between the floor above and the ceiling below that it's still showing up even after you've fixed the leak. However, if you're seeing drops that's probably not the case. If the ceiling is still open, look for any moisture in or on whatever materials are there.
    – FreeMan
    Dec 11, 2018 at 15:31
  • Ceiling is still open. I put a kitchen towel paper to cover the hole and track the drops. Dec 11, 2018 at 16:26
  • "Paper towel to track the drops" suggests that the source pipe or fixture is there and visible. Perhaps using your phone's video mode with light , you could get a better view in the ceiling. Is there other pipes there other then the toilet drain? Pipe to the tub drain? Water pipes? My suspicion is similar to that of your plumber. My house has cast iron drain pipes(not an issue usually)but has a lead toilet flange. The flange being lead tended to move and leaked at the gasket. The solution to my problem was a steel flange plate mounted to the floor. Toilet bolts kept everything together.
    – user68386
    Dec 12, 2018 at 3:00
  • 3 trips by the plumber. Wax seal changed in one toilet and entire toilet changed in the other (started as a wax ring change but the plumber said the 12 inch rough doesn't sit properly so I was asked to get a 10 inch rough). At the end of all this - the leak still exists. Any ideas/ suggestion on further troubleshooting? There is a T junction at the point. I now have paper wrapped around the vertical pipe, paper above and under the horizontal pipe. Dec 24, 2018 at 3:08
  • Condensate or rain coming down the vents?
    – peinal
    Sep 27, 2019 at 16:10

1 Answer 1


Condensation on the vent pipe (warm pipe from venting the shower / sink drain hitting cold air in the attic space)? If it only started happening in winter that would be my suspicion.

  • Condensation IN the vent pipe. Jan 25, 2020 at 15:20

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